Figure 1.

Effect of cytokine stimulation on matrix metalloproteinase (MMP) gene expression in normal or degenerate nucleus pulposus (NP) cells. Normal or degenerate NP cells were cultured in alginate pellets and stimulated by the addition of 10 ng/mL tumour necrosis factor-alpha (TNF-α) (a) or interleukin-1-beta (IL-1β) (b). Quantitative real-time polymerase chain reaction was used to analyse the effect of cytokine stimulation on gene expressions of MMP-3, -9 and -13. All samples are relative to the housekeeping gene GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and normalised back to untreated controls. Results are given as mean ± standard error of the mean (n = 3). *P ≤ 0.05 when compared with untreated controls.